The invention relates to a power supply device comprising:                a DC power supply providing a limited voltage or current on outputs for power supply of a lighting system with light-emitting diodes, said power supply comprising voltage measuring means and current measuring means to monitor a supply voltage and current, and        voltage or current selection means connected to said power supply to select the voltage or current to be applied to said lighting system with light-emitting diodes.        
The invention also relates to a lighting assembly with light-emitting diodes comprising at least one power supply designed to be connected to an electric power supply system, and at least one lighting system with light-emitting diodes connected to said at least one power supply device.
The invention also relates to a power supply method for a lighting system with light-emitting diodes comprising:                selection of a supply voltage or current to be applied to said lighting system with light-emitting diodes, and        monitoring of said supply voltage or current.        